In conventional time division multiple access communication networks, the acquisition of synchronization by a slave station from a reference station is generally provided by including separate synchronization patterns in the control messages broadcast from the master station. These separate synchronization patterns can occupy a substantial bandwidth in the overall data transmission stream.
Several attempts have been made in the prior art to incorporate synchronization codes in the data stream. For example, R. A. Scholtz, "Codes with Synchronization Capability," IEEE Transactions on Information Theory, Volume IT-12, No. 2, April 1966, pages 135-142 discloses synchronizable codes having the property that the punctuation at a given position in a code symbol stream can be determined by observing other code symbols in the neighborhood of the position in question. The Scholtz technique however still has the drawback that specific and unique synchronization bit patterns are present in the data stream. Other attempts have been made in the prior art to achieve frame synchronization in a TDMA transmission network, wherein a frame synchronizer identifies the framing bits in a serial data stream by examining all of the bits in the frame simultaneously and comparing corresponding bits in adjacent frames for the pattern indicative of a framing bit. This type of prior art system includes a frame bit detector and a circuit for producing a locally originated signal at the estimated time of arrival of the frame bits, and further includes a comparison circuit to indicate the loss of synchronization when an accumulated count of the locally originated signal exceeds the accumulated count of the detected frame bits, by a predetermined threshold. This approach, however, also suffers the drawback that additional data bits in the data stream must be employed. Still other attempts have been made in the prior art to achieve synchronization by searching for a special sequence of bits having an auto correlation impulse pattern. These techniques also suffer from the defect that additional, independent bits must be included in the data stream to enable the acquisition of synchronization.